Reversible addition–fragmentation chain transfer (RAFT) was applied to the copolymerization of styrene and maleic anhydride. The product had a low polydispersity and a predetermined molar mass. Novel, well‐defined polyolefin‐based block copolymers were prepared with a macromolecular RAFT agent prepared from a commercially available polyolefin (Kraton L‐1203). The second block consisted of either polystyrene or poly(styrene‐co‐maleic anhydride). Furthermore, the colored, labile dithioester moiety in the product of the RAFT polymerizations could be removed from the polymer chain by UV irradiation. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3596–3603, 2000

The diffusion coefficients of oligomeric radicals in monomer-polymer systems have a major influence on properties such as polymerization rates and molecular weight distributions. The present work reports the results of an extensive set of studies of diffusion coefficients of rubbery ternary systems comprising polymer, diluent, and oligomer, determined by pulsed-field-gradient NMR, at 25 and 40°C. Oligomers of methyl methacrylate (MMA) and of butyl methacrylate (BMA) were synthesized by using a catalytic cobalt chain transfer agent to produce macromonomers with a terminal double bond. Where necessary, these were fractionated by preparative GPC to obtain samples ranging from dimeric to decameric; typical polydispersities were 1.08. Pulsed-field gradient NMR is facilitated by being able to monitor the proton NMR of the CH 2 hydrogens on the double bond. Matrixes used were high molecular weight polyMMA and polyBMA, the weight fraction of polymer (wp) being varied by adding appropriate amounts of diluent (the saturated equivalents of MMA and BMA, viz., methyl isobutyrate and butyl isobutyrate). Above c* (the concentration at which chains start to overlap), all data for diffusion coefficients Di of an oligomer of degree of polymerization i could be fitted with acceptable accuracy by D1(wp)/Di(wp) ) i 0.664 + 2.02w p , for both BMA and MMA oligomers in both MMA and BMA matrixes; the same relation also fits earlier data on styrene oligomers in polystyrene. If more accurate scaling parameters are obtained experimentally for smaller oligomers, these can be used to predict data for higher oligomers with even better reliability. For MMA monomer in pMMA, where free-volume parameters are available, the predicted dependences of monomer diffusion coefficient on w p and temperature are in accord with experiment.

This work reports the synthesis of high molecular weight poly(TEMPO methacrylate) and the molecular weight influence on electrochemical properties.

SummaryChemotherapy resistance is a major contributor to poor treatment responses and It is therefore possible to understand CSC drug resistance by exploring the effect of hypoxia on these resistance features.Understandingtheseinteractionsandtheunderlyingmechanisms

Extralieferung: Ein effektiver Impfstoff gegen Gruppe‐A‐Streptokokken wird von einem Liefersystem gebildet, das aus genau definierten nanoskaligen dendritischen Strukturen besteht (siehe Bild). Die Strukturen präsentieren mehrere Kopien der minimalen B‐Zellepitope, die auf der Oberfläche der Nanopartikel die optimale Konformation haben. Die Nanopartikel können ohne Zusatz eines Hilfsmittel verabreicht werden.